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Old 03-11-2012, 03:34 PM   #21
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Update,

I got the idle valve test working. I was making the stupid mistake of turning on the test first and then changing the step values. This just sent the idle to 3000 rpm.

So then I changed the values and THEN turned on the test. At the suggested low values of 15-30 the idle remained the same (1350rpm). When I changed it to 90 it jumped to 3000rpm again. I presume this shows the idle valve is working. Also, when I disconnected the plug on the valve, the revs jumps up about 1000rpm.

So, it looks to mee like its working, but just not enough.

One other thing, the idle rpm increases as the engine warms up, ie first start its 1500rpm, then drops steadily as engine warms up to operating temp. Then as the car is driven the idle gradually creeps up (driving through traffic) to 1700rpm

Going to change the injectors in next few days (550cc EV14s). I wonder will this solve it or make it worse?

Anyone any suggestions?
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Old 03-11-2012, 04:48 PM   #22
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Quote:
Originally Posted by andrew View Post
So then I changed the values and THEN turned on the test. At the suggested low values of 15-30 the idle remained the same (1350rpm). When I changed it to 90 it jumped to 3000rpm again. I presume this shows the idle valve is working. Also, when I disconnected the plug on the valve, the revs jumps up about 1000rpm.
This just proves that you have an air leak. With the idle valve set to close position (anything lower than 30) the car should be running 100% off the idle air screw, in which case you've got it wound so far out it is idling at 1350rpm or you've got a small air leak allowing the car to get air in an uncontrolled way. I'd put money on an air leak, as that would change with temperature as the metal surfaces expand etc. Has the throttle body been apart with the IAC (idle valve) removed? There are small gaskets and some of them can perish and allow lots of air in. Also, there is the warm start valve up on the intake, it may also be at fault.

Again, you've got something wrong as it isn't the megasquirt its the car.
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Old 03-12-2012, 07:12 PM   #23
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Thanks Grant,

Your reply makes sense, I have not taken the throttle body off or the IAC. I did disconnect some coolant hoses to the warm start valve on the throttle body when changing the injectors. I am getting a mechanic to change to injectors again tomorrow. Maybe if something was disturbed it might be found and put right during the injector instal. If not I'll just drive the car into a lake on boost and look for bubbles !!!
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Old 03-12-2012, 07:41 PM   #24
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Just let the car idle then spray around where you think the leak might be with some carb cleaner. It doesn't take much, just a little squirt. That's how I found my fuel injector vacuum leak. If there is a vacuum leak, spraying the area will cause a change in the idle.
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Old 03-13-2012, 07:10 PM   #25
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Ok, Finally sorted this when changing my injectors to EV14's

As Grant diagnosed there was a vacuum leak under the warm up valve. My mechanic found it while changing the injectors. The car now idles about 850rpm with the idle screw adjust out. previously it was in all the way.

Just need to retune my VE table now for new injectors and its down to the track on 30th March.
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Old 03-13-2012, 07:15 PM   #26
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Nice. Glad you got it sorted!
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